Plate nut assembly

ABSTRACT

A plate nut assembly is provided in which a projection provided on the nut has a centering guide function relative to a circular hole so that the projection reliably fits in the circular hole to prevent displacing of the nut assembly, even if an external force is applied in a direction perpendicular to the axis of a bolt. Around an entrance of the threaded hole one side of the nut, within such a range as to be within the diameter of a hole formed beforehand in a wall or the like at its portion where the nut is inserted, a protrusion is formed on one side of the nut around the threaded hole, so that the height decreases as it is farther from around the threaded hole, and a recess having substantially the same outer diameter as the protrusion is formed around the threaded hole on the other side of the nut, the recess having opposed end walls inclined such that the distance between the opposed end walls decreases as they go deeper.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a plate nut assembly used to fasten an instrument or the like to a wall or the like to the back of which hands cannot reach.

[0002] When an instrument or the like is bolted to such a member, a plate nut assembly is used. As disclosed in Japanese patent publication 10-306818, it includes a rectangular plate-like nut having a threaded hole extending in the thickness direction, and a bendable support tongue piece fixed to the nut. The tool is fixed to the wall by forming a circular hole in a wall or the like, inserting the nut through the circular hole to the back side of the wall, pulling back the support tongue piece to press the nut against the back side of the wall, and threading a bolt through the instrument into the threaded hole of the nut.

[0003] When such a plate nut assembly is used, the outer diameter of the bolt to be threaded into the nut is limited to a rather small value compared to the diameter of the circular hole formed in the wall. Thus, if an external force is applied in a direction perpendicular to the axis of the bolt after the mounting of the instrument, the axis of the bolt tends to displace in the direction of the external force until it abuts the peripheral edge of the circular hole with the bolt and the plate nut assembly in threaded engagement with each other.

[0004] In order to prevent such displacement, with a conventional plate nut assembly, a protrusion protruding in a step-like manner is provided around the entrance of the threaded hole of the nut on one side thereof. After inserting the nut into a circular hole of the wall, when the support tongue piece is pulled back to press the nut against the back side of the wall, the protrusion fits in the circular hole formed in the wall.

[0005] But since the protrusion on the nut of the conventional plate nut element is formed in such a shape that protruding surfaces protrude in the form of flat steps, although effects are obtained if the protrusion fits snugly in the circular wall of the wall or the like, the protrusion has no guiding function in centering the nut relative to the circular hole so that its threaded hole will be coaxial with respect to the circular hole. Thus, as described above, when the nut is pressed against the back side of the wall by pulling back the support tongue piece, the protrusion abuts the back side of the wall, so that the nut may displace relative to the circular hole.

[0006] An object of this invention is to provide a plate nut assembly in which the protrusion provided on the nut has a guiding function in centering the nut relative to the circular hole so that its threaded hole will be coaxial with respect to the circular hole and the protrusion reliably fits with respect to the circular hole so as not to displace in the direction of an external force even if the external force is applied in a direction perpendicular to the axis of the bolt.

SUMMARY OF THE INVENTION

[0007] According to this invention, there is provided a plate nut assembly comprising a rectangular plate-like nut formed with a threaded hole extending in a thickness direction and a support tongue piece having one end thereof fixed to the nut at a corresponding end thereof, characterized in that a protrusion is formed on one side of the nut around the threaded hole, so that the height decreases as it is farther from around the threaded hole, and a recess having substantially the same outer diameter as the protrusion is formed around the threaded hole on the other side of the nut, the recess having opposed end walls inclined such that the distance between the opposed end walls decreases as they go deeper.

[0008] According to this invention, by forming a recess on the other side of the nut by pressing, material of the nut swells toward the one side, thereby forming the protrusion on the one side of the nut. Thus, it is possible to economically produce the nut.

[0009] Also, by inclining the peripheral wall of the recess on the other side of the nut so that the distance between the opposed end walls decreases as they go deeper, it is possible to prevent the pressing pressure for forming the recess from locally concentrating on the projection formed on the one side and the internal structure of the nut from getting destroyed along the outer contour of the nut.

[0010] Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1A is a perspective view showing the plate nut assembly embodying this invention;

[0012]FIG. 1B is a perspective view of the nut of the same as seen from its back side;

[0013]FIG. 1C is an enlarged sectional view of the nut;

[0014]FIG. 2A is a vertical sectional view showing how the plate nut assembly is being inserted into a circular hole formed in a wall;

[0015]FIG. 2B is a vertical sectional view showing the nut brought into abutment with the back side of the wall;

[0016]FIG. 3 is an enlarged sectional side view showing how an instrument is clamped by use of the plate nut assembly of this invention; and

[0017]FIG. 4 is a vertical sectional enlarged front view showing the clamped state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] The embodiment of this invention will be described with reference to FIGS. 1 to 4.

[0019] As in FIG. 1, the plate nut assembly 1 of this invention comprises a rectangular plate-like nut 3 made of a metal, having a predetermined thickness and formed with a threaded hole 2 extending in the thickness direction in the central portion, and a support tongue piece 4 having one end thereof fixed to the nut 3.

[0020] The nut is formed with a protrusion 5 on one side thereof around the entrance of the threaded hole 2, and a recess 6 on the other side around the exit of the threaded hole 2. The recess 6 has an outer diameter substantially equal to that of the protrusion 5 formed on the one side.

[0021] The protrusion 5 has a height decreasing as it gets farther from the outer periphery of the threaded hole 2. But the protrusion 5 is within the diameter of a circular hole B formed beforehand in a wall A shown in FIGS. 3 and 4. The protrusion 5 has a substantially elliptical shape with the longitudinal ends formed arcuate so as to fit in the circular hole B and both longitudinal sides formed straight. Further, the protrusion 5 has its inner edge perpendicular to the surface of the nut 3 with its protruding surface inclined outwardly downwardly from the perimeter of the threaded hole 2 arcuately or in a straight line.

[0022] On the other side of the nut 3 around the exit of the threaded hole 2, the recess 6 is formed which is substantially equal in the outer shape to the protrusion 5 formed on the one side. The opposed end walls of the recess 6 are inclined so that the distance between the opposed end walls decrease toward the bottom of the recess 6.

[0023] The protrusion 5 on the one side of the nut 3 and the recess 6 on the other side are formed simultaneously by pressing. Specifically, by pressing the nut 3 from the other side with a mold having a protrusion for forming the recess 6 and the one side of the nut 3 supported by a mold having a recess for forming the protrusion 5, material of the nut 3 swells toward the one side and simultaneously the recess 6 is formed in the other side. By forming the swollen portion with the recess of the mold, the protrusion 5 is formed. By forming the protrusion 5 and the recess 6 simultaneously, economical production of the nut 3 becomes possible, compared with if the protrusion 5 is formed by machining such as cutting.

[0024] By inclining the opposed end walls of the recess 6 as described above, it is possible to prevent the pressing pressure for forming the recess 6 from locally concentrating on the protrusion 5 formed on the one side, thereby destroying the inner structure of the nut, and to improve releasability of the nut 3 after molding from the protrusion of the mold for forming the recess 6.

[0025] The support tongue piece 4 has a thin metallic plate 7 having a width substantially equal to that of the nut 3 and an opening 8 for receiving the protrusion 5 of the nut 3. Bent portions 9 are provided on both sides of the metallic plate 7 near one end and a fixed end 10 is fitted on the nut 3 from the one side thereof. An enlarged portion 11 is provided at the other end of the metallic plate 7. It has a width greater than the diameter of a circular hole B formed in the wall A so that the nut 3 just fits. The metallic plate 7 is bent at a position 12 nearer to its fixed end than is the center of the threaded hole 2 and it is inclined relative to the fixed end 10 at the portion from the bent portion.

[0026] The support tongue piece 4 has the fixed end 10 fitted on the nut 3 with the protrusion 5 of the nut 3 partially fitting in the opening 8. The fixed end is substantially the front half portion of the nut 3 relative to the inserting direction of the nut 3. The fixed end 10 and the nut 3 are fixed together e.g. by welding, bonding, pressing, threading or caulking.

[0027] The plate nut assembly of this invention is structured as described above. For use, a circular hole B into which the nut 3 can be inserted is formed in a wall A beforehand, and the nut 3 is inserted into the hole B in the wall A as shown in FIG. 2A while pressing a portion of the support tongue piece 4 near the enlarged portion 11 so that it contacts the nut.

[0028] After completely inserting the nut to the back of the wall A, as shown in FIG. 2B, the enlarged portion 11 of the support tongue piece 4 is pulled toward this side until the nut 3 is superposed on the back side of the wall A. At this time, since the nut 3 has its protrusion 5 opposing the back side of the wall A and the protrusion 5 is formed with an inclined or tapered surface so that as it is farther from around the threaded hole 2, its height decreases, when the nut 3 is pulled toward the back of the wall A, the protrusion 5 abuts the peripheral edge of the opening at the end of the circular hole B and performs a self-centering function with the inclined surface. As the nut 3 moves toward the axis of the circular hole B, the protrusion 5 completely fits into the circular hole B. Thus, the nut 3 can be positioned relative to the circular hole B such that its threaded hole 2 will be substantially coaxial with the circular hole B.

[0029] In this state, as shown in FIGS. 3 and 4, by bending the portion of the support tongue piece 4 protruding from the wall A or the like toward the wall A, superposing a tool C on the wall A and the bent portion of the tongue piece 4, and threadedly tightening a bolt D passed through the tool C and into the threaded hole 2 of the nut 3, it is possible to fix the tool C to the wall A.

[0030] As described above, since the protrusion 5 provided on the nut 3 completely fits in the circular hole B in the wall A, even if an external force is applied in a direction perpendicular to the axis of the bolt D after mounting of the tool C, the external force is borne on the portion of the protrusion 5 fitted in the circular hole B, so that the tool C would not displace in the direction of the external force after fixing.

[0031] According to this invention, because the recess formed on the nut is formed so as to incline or taper such that the distance between the opposed end walls decreases as they go deeper, it is possible to prevent the pressing pressure for forming the recess from locally concentrating on the projection formed on the one side and the internal structure of the nut from getting destroyed along the outer contour of the nut.

[0032] Also, releasability of the nut from the protrusion of the mold for forming the recess is improved. 

What is claimed is:
 1. A plate nut assembly comprising a rectangular plate-like nut formed with a threaded hole extending in a thickness direction and a support tongue piece having one end thereof fixed to said nut at a corresponding end thereof, characterized in that: a protrusion is formed on one side of said nut around said threaded hole, so that the height decreases as it is farther from around said threaded hole, and a recess having substantially the same outer diameter as said protrusion is formed around said threaded hole on the other side of said nut, said recess having opposed end walls inclined such that the distance between said opposed end walls decreases as they go deeper. 